1. Field of the Invention
The present invention relates to a thin-film magnetic circuit board, and to a magnetic head using such a circuit board. In particular, the invention is concerned with a magnetic head using a novel type of thin-film magnetic circuit board, which magnetic head can be manufactured with high efficiency, assuring relatively small magnetic resistance and improved operating efficiency.
2. Discussion of the Prior Art
As a type of magnetic heads used with a floppy disk drive (FDD), hard disk drive (HDD) or other devices, there is known a so-called bulk-type magnetic head which includes a generally ring-shaped magnetic head core formed of a magnetic material such as ferrite, and a coil attached to the head core. An example of the bulk-type magnetic head is shown in FIG. 23, in which a pair of generally C-shaped core halves 2, 2 are butted and bonded together, to thereby provide a magnetic head core 6 having an annular magnetic path (magnetic circuit) and a magnetic gap 4 formed at a point of the circumference thereof so as to extend in a direction perpendicular to the magnetic path. The magnetic head core 6 has a central aperture 8 which is utilized for winding a coil 10 on the head core 6.
To produce this bulk-type magnetic head, however, the coil 10 must be wound through a considerably small aperture 8 formed through the magnetic head core 6. This coil-winding procedure is usually manually effected, and therefore accounts for about 20% of the whole cost of manufacturing the magnetic head. Thus, the above type of magnetic head is manufactured with low efficiency at an undesirably increased cost.
In recent years, there is proposed a so-called thin-film type magnetic head which employs a magnetic film or films and an electrically conductive film formed by a thin-film forming method such as photoetching, to provide a magnetic circuit and a coil, respectively. An example of such a magnetic head is illustrated in FIG. 24, which is constructed such that a lower magnetic layer 14, a coil 16 and an upper magnetic layer 18 are superposed on a non-magnetic substrate 12 in the order of description, by a suitable thin-film forming method, and such that the lower and upper magnetic layers 14, 18 cooperate with a magnetic gap 20 formed therebetween to constitute a closed magnetic circuit.
While the coil 16 of the above magnetic head may be easily formed by the thin-film forming method, it is extremely difficult to form the upper and lower magnetic layers 18, 14 of the magnetic circuit by the same thin-film forming method so that the layers 18, 14 have a sufficiently large thickness. Consequently, the magnetic head of this type suffers from undesirably increased magnetic resistance in the magnetic circuit, resulting in deteriorated operating efficiency of the head.
Namely, neither of the bulk-type and thin-film type of magnetic heads is able to meet both requirements, i.e., high efficiency in producing the magnetic head and excellent operating characteristics of the head. Thus, the known magnetic heads have some room for improvement in the above respects.